src/codec/SkCodec.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkCodec.h"
#include "SkData.h"
#include "SkCodec_libbmp.h"
#include "SkCodec_libpng.h"
#include "SkStream.h"

struct DecoderProc {
    bool (*IsFormat)(SkStream*);
    SkCodec* (*NewFromStream)(SkStream*);
};

static const DecoderProc gDecoderProcs[] = {
    { SkPngCodec::IsPng, SkPngCodec::NewFromStream },
    { SkBmpCodec::IsBmp, SkBmpCodec::NewFromStream }
};

SkCodec* SkCodec::NewFromStream(SkStream* stream) {
    if (!stream) {
        return NULL;
    }
    for (uint32_t i = 0; i < SK_ARRAY_COUNT(gDecoderProcs); i++) {
        DecoderProc proc = gDecoderProcs[i];
        const bool correctFormat = proc.IsFormat(stream);
        if (!stream->rewind()) {
            return NULL;
        }
        if (correctFormat) {
            return proc.NewFromStream(stream);
        }
    }
    return NULL;
}

SkCodec* SkCodec::NewFromData(SkData* data) {
    if (!data) {
        return NULL;
    }
    return NewFromStream(SkNEW_ARGS(SkMemoryStream, (data)));
}

SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
    : INHERITED(info)
    , fInfo(info)
    , fStream(stream)
    , fNeedsRewind(false)
{}

bool SkCodec::rewindIfNeeded() {
    // Store the value of fNeedsRewind so we can update it. Next read will
    // require a rewind.
    const bool neededRewind = fNeedsRewind;
    fNeedsRewind = true;
    return !neededRewind || fStream->rewind();
}